2022年9月5日四川泸定发生MS 6.8地震，中国地震台网中心JEEW预警处理系统有效处理并产出本次地震的预警信息。本次地震发生在四川地震预警区内，震后6.4 s发布首次预警处理结果，使用7个台站数据，与统一编目结果相比，震中位置偏差3.7 km，震级偏差-0.8，盲区半径15 km。随着参与定位台站的数量增多，震中位置及震级偏差逐渐减小，但盲区半径不断增大，预警效益随之减小。震后39 s，使用337个台站数据后，预警震级稳定在6.4。预警震级整体偏小主要原因是，震后短期内有效波形数据较少，较短时间窗内的波形振幅不能反映震级的实际大小。另外，部分近场基准站地震波形限幅，且ML震级存在饱和，也导致震级被低估。本次地震预警效果较好，但震级准确性有待进一步提升。为提高预警系统的减灾效能，在不断改进震级算法的同时，也需完善预警信息发布策略。
On September 5, 2022, the MS 6.8 earthquake occurred in Luding, Sichuan. The JEEW data processing system of China Earthquake Networks Center effectively processed and produced the early warning information. This earthquake occurred within the Sichuan earthquake early warning network. The first early warning processing result was released 6.4 s after the earthquake by using 7 stations. Compared with the unified catalog, the first early warning processing result shows that the deviation of the epicenter position is 3.7 km, and the magnitude deviation is -0.8 with the blind zone of 15 km. With more stations getting involved in locating, the deviation of the epicenter position and magnitude gradually decreases, but the blind zone continues to increase, and the early warning benefits decrease. 39 s after the earthquake, the early warning magnitude is stable at 6.4 by using 337 stations. The main reason for the overall smaller early warning magnitude is that there are few effective waveform data in the short term after the earthquake, and the waveform amplitude in the short time window cannot reflect the actual magnitude. In addition, the limitation of the seismic waveform at some near-field reference stations and the saturation of ML magnitude also lead to magnitude underestimation. In this earthquake, the effect of the early warning isgood, but the accuracy of magnitude needs to be further improved. In order to improve the disaster reduction efficiency of the early warning system, it is necessary to improve the early warning release strategy while continuously improving the magnitude algorithm.
2022,43（6）: 131-141 收稿日期：2022-10-31
DOI：10.3969/j.issn.1003-3246.2022.06.018
基金项目：中国地震台网中心青年基金（项目编号：122302140）
作者简介：徐佳静(1992-),女,工程师,主要从事地震速报和预警等方面的研究工作。E-mail:xujiajing@seis.ac.cn
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